OfficePad Stationery

Office Interior, Air Conditioners

Fellowes AeraMax Professional AM2 Air Purifier Fellowes AeraMax Professional AM2 Air Purifier
£982.00 exc vat | £1178.40 inc vat | Only 8 left
Wall mounted and hard wired, cleans areas up to 30m squared , slim profile, ADA compliant, flexible Integration, auto-detecting technology, removes 99.9% of allergens and viruses using True HEPA filter.
Fellowes AeraMax Professional AM3 Air Purifier Fellowes AeraMax Professional AM3 Air Purifier
£1478.00 exc vat | £1773.60 inc vat | Stock : 7
Wall mounted, No plug - hard-wired, 5 fan speeds, clean areas up to 55m squared , enviroSmart Technology, 4 levels of Filtration, front-loading filter change, Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser.
Fellowes AeraMax Professional AM3 PC Pureview Air Purifier Fellowes AeraMax Professional AM3 PC Pureview Air Purifier
£1819.00 exc vat | £2182.80 inc vat | Stock : 6
Wall mounted, No plug - hard-wired, Pureview technology, 5 fan speeds, clean areas up to 55m squared , enviroSmart Technology, 4 levels of Filtration, Fitted Plug, front-loading filter change, PM2.5 Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser.
Fellowes AeraMax Professional AM3 S Free Standing Air Purifier Fellowes AeraMax Professional AM3 S Free Standing Air Purifier
£1637.00 exc vat | £1964.40 inc vat | Stock : 7
Free-standing Air Purifier, 5 fan speeds, clean areas up to 55m squared , enviroSmart Technology, 4 levels of Filtration, Fitted Plug, front-loading filter change, Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser, interchangeable EU/UK plug.
Fellowes AeraMax Professional AM3 S PC Free Standing Pureview Air Purifier Fellowes AeraMax Professional AM3 S PC Free Standing Pureview Air Purifier
£1884.00 exc vat | £2260.80 inc vat | Stock : 6
Free-standing Air Purifier, Pureview technology, 5 fan speeds, clean areas up to 55m squared , enviroSmart Technology, 4 levels of Filtration, Fitted Plug, front-loading filter change, PM2.5 Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser, interchangeable EU/UK plug.
Fellowes AeraMax Professional AM4 Air Purifier Fellowes AeraMax Professional AM4 Air Purifier
£2371.00 exc vat | £2845.20 inc vat | Stock : 5
The AeraMax Professional AM4 air purifier cleans air in 60 - 110 square metre common areas such as schools, offices, waiting rooms, restrooms, and other areas of high concentrations of contaminants. True HEPA filter captures 99.97% of airborne contaminants including viruses and allergens.
Fellowes AeraMax Professional AM4 PC Pureview Air Purifier Fellowes AeraMax Professional AM4 PC Pureview Air Purifier
£2547.00 exc vat | £3056.40 inc vat | Stock : 4
Wall mounted, No plug - hard-wired, 5 fan speeds, clean areas up to 110m squared , enviroSmart Technology, 4 levels of Filtration, front-loading filter change, PM2.5 Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser.
Fellowes AeraMax Professional AM4 S Free Standing Air Purifier Fellowes AeraMax Professional AM4 S Free Standing Air Purifier
£2531.00 exc vat | £3037.20 inc vat | Stock : 4
Free-standing Air Purifier, 5 fan speeds, clean areas up to 110m squared , enviroSmart Technology, 4 levels of Filtration, Fitted Plug, front-loading filter change, Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser, interchangeable EU/UK plug.
Fellowes AeraMax Professional AM4 S PC Free Standing Pureview Air Purifier Fellowes AeraMax Professional AM4 S PC Free Standing Pureview Air Purifier
£2660.00 exc vat | £3192.00 inc vat | Stock : 4
Free-standing Air Purifier, Pureview technology, 5 fan speeds, clean areas up to 110m squared , enviroSmart Technology, 4 levels of Filtration, Fitted Plug, front-loading filter change, PM2.5 Odour/VOC Motion and Sound Sensor Technology, PlasmaTrue Ioniser, interchangeable EU/UK plug.
Fellowes AeraMax Professional Carbon Filter for AM2 Fellowes AeraMax Professional Carbon Filter for AM2
£145.99 exc vat | £175.19 inc vat | Only 1 left
45mm Carbon filter for use with the AeraMax Professional AM2 Air Purifier, commercial grade activated carbon filter, dsorbs a wide range of volatile organic compounds (VOCs) and odors, one-year estimated filter life (dependant on usage), pack of 1.
Fellowes AeraMax Professional Carbon Filter with Pre-Filters for AM3 and AM4 [Pack of 4] Fellowes AeraMax Professional Carbon Filter with Pre-Filters for AM3 and AM4 [Pack of 4]
£240.99 exc vat | £289.19 inc vat | Only 7 left
5mm carbon filter with pre filters, commercial grade activated carbon filter which adsorbs a wide range of volatile organic compounds (VOCs) and odors, includes separate pre-filter to capture larger particulate, 6-month estimated filter life, pack of 4.
Fellowes AeraMax Professional Carbon Filters for AM3 and AM4 [Pack of 2] Fellowes AeraMax Professional Carbon Filters for AM3 and AM4 [Pack of 2]
£343.99 exc vat | £412.79 inc vat | Stock : 18
50mm Carbon Filter, commercial grade activated carbon filter, replacement filter for AeraMax Pro AM 3 and AM4 Air Purifiers, includes separate pre-filter to capture larger particulate, One-year estimated filter life, pack of 2.
Fellowes AeraMax Professional Hybrid Filter for AM2 Fellowes AeraMax Professional Hybrid Filter for AM2
£145.99 exc vat | £175.19 inc vat | Stock : 69
45mm Hybrid filter for use with the AeraMax Professional AM2 Air Purifier, standard replacement filter, half True HEPA and half Activated Carbon, filter captures 99.97% of airborne particles, antimicrobial Treatment, One-year estimated filter life (dependant on usage), pack of 1.
Fellowes AeraMax Professional Hybrid Filters for AM3 and AM4 [Pack of 2] Fellowes AeraMax Professional Hybrid Filters for AM3 and AM4 [Pack of 2]
£409.99 exc vat | £491.99 inc vat | Stock : 25
50mm Hybrid Filter, contains 50% Carbon and 50% True HEPA, replacement filter for AeraMax Pro AM 3 and AM4 Air Purifiers, captures 99.97% of airborne particles, antimicrobial treatment, One-year estimated filter life, pack of 2.
Fellowes AeraMax Professional Pre-Filter for AM3 and AM4 [Pack of 4] Fellowes AeraMax Professional Pre-Filter for AM3 and AM4 [Pack of 4]
£36.49 exc vat | £43.79 inc vat | Only 3 left
Replacement Pre Filters, replacement for AeraMax Pro AM 3 and AM4 Air Purifiers, captures large particulates like dust and hair, One-year estimated filter life (changed with Carbon filter), pack of 4. Pre-filters capture large particulates like dust and hair and keep carbon filters working effectively.
Fellowes AeraMax Professional Stand Accessory for AM2 Fellowes AeraMax Professional Stand Accessory for AM2
£51.99 exc vat | £62.39 inc vat | Only 2 left
Floor stand accessory for use with AeraMax PRO AM2 Air Purifier, allows low-profile, portable placement of AeraMax PRO AM2, sturdy design with a quick no tool assembly, allows mobility for placement in other rooms.
Fellowes AeraMax Professional True HEPA Filter for AM2 Fellowes AeraMax Professional True HEPA Filter for AM2
£88.49 exc vat | £106.19 inc vat | Only 1 left
45mm HEPA filter for use with the AeraMax Professional AM2 Air Purifier, captures 99.97% of airborne particles, antimicrobial treatment, One-year estimated filter life (dependant on usage), pack of 1. *** CLEARANCE ITEM - LIMITED STOCK AVAILABILITY AT THIS PRICE *** True HEPA filter captures 99.97% of airborne particles at the size 0.3 microns, including pollen, ragweed and other allergens, viruses, germs, dust mites, mold spores, pet dander and cigarette smoke.
Fellowes AeraMax Professional True HEPA Filters for AM3 and AM4 [Pack of 2] Fellowes AeraMax Professional True HEPA Filters for AM3 and AM4 [Pack of 2]
£388.99 exc vat | £466.79 inc vat | Stock : 12
45mm True HEPA Filter, standard replacement filter for AeraMax Pro AM 3 and AM4 Air Purifiers, captures 99.97% of airborne particles, antimicrobial treatment, One-year estimated filter life, pack of 2. Part of the standard replacement filter configuration for all variants of AeraMax Pro-AM 3 and AM4 Air Purifiers.
Fellowes AeraMax SE Air Purifier Fellowes AeraMax SE Air Purifier
£717.00 exc vat | £860.40 inc vat | Only 1 left
Large room coverage: Recommended for rooms up to 80m squared , Powerful ACH: 80m squared at 3 Air Changes Per Hour (ACH) and 50m squared at 5 ACH, Allergy protection with H13 HEPA Filtration: Captures up to 99.95% of particles as small as 0.1 microns including allergens.
Fellowes AeraMax SE Combo Filter Fellowes AeraMax SE Combo Filter
£195.99 exc vat | £235.19 inc vat | Stock : 17
One Filter with Three Functions: Combined Pre-Filter H13 HEPA and Carbon Filter, H13 HEPA Filtration: Captures up to 99.95% of particles as small as 0.1 microns including allergens pollen dust pet dander and smoke, One year-long-lasting performance.
Fellowes AeraMax SV Air Purifier Fellowes AeraMax SV Air Purifier
£1152.00 exc vat | £1382.40 inc vat | Stock : 9
Large room coverage: Recommended for rooms up to 130m squared , Powerful ACH: 130m squared at 3 Air Changes Per Hour (ACH) and 80m squared at 5 ACH, Allergy protection with H13 HEPA Filtration: Captures up to 99.95% of particles as small as 0.1 microns including allergens.
Fellowes Carbon Filter AeraMax 10 Fellowes Carbon Filter AeraMax 10
£26.79 exc vat | £32.15 inc vat | Stock : 109
Fellowes carbon filter replacement for the AeraMax 10 model.
Fellowes Carbon Filter AeraMax 30 Fellowes Carbon Filter AeraMax 30
£35.49 exc vat | £42.59 inc vat | Only 2 left
Fellowes carbon filter replacement for the AeraMax 30 model.
Fellowes Carbon Filter for PT65 Pet Air Purifier [Pack of 2] Fellowes Carbon Filter for PT65 Pet Air Purifier [Pack of 2]
£18.79 exc vat | £22.55 inc vat | Stock : 23
Replacement Carbon filter to fit PT65 Pet air purifier, Pack of 2.
Fellowes CF230 Carbon Filter Fellowes CF230 Carbon Filter
£24.79 exc vat | £29.75 inc vat | Stock : 13
Replacement Carbon Filter to fit AP-230.
Fellowes Hepa Filter AeraMax 10 Fellowes Hepa Filter AeraMax 10
£29.79 exc vat | £35.75 inc vat | Only 1 left
Fellowes HEPA filter replacement for the AeraMax 10 model.
Fellowes Hepa Filter AeraMax 30 Fellowes Hepa Filter AeraMax 30
£51.49 exc vat | £61.79 inc vat | Stock : 27
Fellowes HEPA filter replacement for the AeraMax 30 model.
Fellowes HEPA Filter for PT65 Pet Air Purifier Fellowes HEPA Filter for PT65 Pet Air Purifier
£35.49 exc vat | £42.59 inc vat | Stock : 100
Replacement HEPA filter to fit PT65 Pet air purifier, Pack of 1.
Fellowes HF230 HEPA Filter Fellowes HF230 HEPA Filter
£40.49 exc vat | £48.59 inc vat | Only 2 left
Replacement HEPA Filter to fit AP-230.
Leitz Replacement Carbon Filter Small [Pack of 3] Leitz Replacement Carbon Filter Small [Pack of 3]
£13.49 exc vat | £16.19 inc vat | Stock : 50
For use with the TruSens Z-1000 Air Purifier, for best results replace carbon layer filter every 3 months, pack of 3 filters. For use with the TruSens Z-1000 Air Purifier. Filter replacement is essential for your air purifier to perform at its best.
Leitz Replacement UV-C Lamp for Leitz TruSens Z2000 Leitz Replacement UV-C Lamp for Leitz TruSens Z2000
£15.49 exc vat | £18.59 inc vat | Only 1 left
For use with the Leitz TruSens Z-2000 Air Purifier, UV reduces the growth of odour-causing microbes, indicator light on the air purifier glows red when it's time to replace the bulb. An important part of the air purification system, a UV bulb destroys germs and bacteria.
Leitz TruSens Z-1000 Allergy and Flu Anti-viral 3-in-1 Carbon Filter Leitz TruSens Z-1000 Allergy and Flu Anti-viral 3-in-1 Carbon Filter
£20.99 exc vat | £25.19 inc vat | Stock : 20
Carbon filter is a replaceable element of the Allergy and Flu HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, compatible with the Allergy and Flu HEPA filter drum for all Leitz TruSens Z-1000 air purifiers.
Leitz TruSens Z-1000 Allergy and Flu Anti-viral 3-in-1 HEPA Filter Drum Leitz TruSens Z-1000 Allergy and Flu Anti-viral 3-in-1 HEPA Filter Drum
£43.49 exc vat | £52.19 inc vat | Stock : 24
HEPA filter with anti-viral coating, 360 degree filtration, best for allergies and flu, efficiency level of 99.97% at 0.3 micron, captures airborne allergens and viruses including the H1N1 flu virus, for use with the Z-1000 Air Purifier.
Leitz TruSens Z-1000 Pet 3-in-1 Carbon Filter Leitz TruSens Z-1000 Pet 3-in-1 Carbon Filter
£23.49 exc vat | £28.19 inc vat | Stock : 10
Carbon filter is a replaceable element of the Pet HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, compatible with the Pet HEPA filter drum for all Leitz TruSens Z-1000 air purifiers.
Leitz TruSens Z-1000 Pet 3-in-1 HEPA Filter Drum Leitz TruSens Z-1000 Pet 3-in-1 HEPA Filter Drum
£43.49 exc vat | £52.19 inc vat | Only 9 left
HEPA filter with washable pre-filter, efficiency level of 99.97% at 0.3 micron, 360 degree filtration, best for pet dander and odours, indicator light glows red on your air purifier when the filter needs to be replaced, Use with Z-1000 Air Purifier.
Leitz TruSens Z-2000 Allergy and Flu Anti-viral 3-in-1 Carbon Filter Leitz TruSens Z-2000 Allergy and Flu Anti-viral 3-in-1 Carbon Filter
£25.79 exc vat | £30.95 inc vat | Stock : 10
Carbon filter is a replaceable element of the Allergy and Flu HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, compatible with the Allergy and Flu HEPA filter drum for all Leitz TruSens Z-2000 and Z-2500 air purifiers.
Leitz TruSens Z-2000 HEPA Filter Drum Leitz TruSens Z-2000 HEPA Filter Drum
£37.79 exc vat | £45.35 inc vat | Stock : 21
For use with the TruSens Z-2000 Air Purifier, 360 degree filtration, carbon prefilter captures odours and certain gases, HEPA Type filter removes pollutants as small as 0.3 microns, truSens combination filter has been engineered to collect microscopic particles allergens and volatile organic components (VOC's), and odorous gases.
Leitz TruSens Z-2000 Pet 3-in-1 Carbon Filter Leitz TruSens Z-2000 Pet 3-in-1 Carbon Filter
£31.49 exc vat | £37.79 inc vat | Stock : 10
Carbon filter is a replaceable element of the Pet HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, compatible with the Pet HEPA filter drum for all Leitz TruSens Z-2000 and Z-2500 air purifiers.
Leitz TruSens Z-2000 Pet 3-in-1 HEPA Filter Drum Leitz TruSens Z-2000 Pet 3-in-1 HEPA Filter Drum
£60.99 exc vat | £73.19 inc vat | Stock : 12
HEPA filter with washable pre-filter, efficiency level of 99.97% at 0.3 micron, 360 degree filtration, best for pet dander and odours, indicator light glows red on your air purifier when the filter needs to be replaced, Use with Z-2000 and Z-2500 Air Purifiers.
Leitz TruSens Z-3000 Allergy and Flu Anti-Viral 3-in-1 Carbon Filter Leitz TruSens Z-3000 Allergy and Flu Anti-Viral 3-in-1 Carbon Filter
£33.99 exc vat | £40.79 inc vat | Stock : 20
Carbon filter is a replaceable element of the Allergy and Flu HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, compatible with the Allergy and Flu HEPA filter drum for all Leitz TruSens Z-3000 and Z-3500 air purifiers.
Leitz TruSens Z-3000 HEPA Filter Drum Leitz TruSens Z-3000 HEPA Filter Drum
£48.99 exc vat | £58.79 inc vat | Stock : 30
For use with the TruSens Z-3000 and Z-3500 Air Purifier, 360 degree filtration, carbon prefilter captures odours and certain gases, HEPA Type filter removes pollutants as small as 0.3 microns, truSens combination filter has been engineered to collect microscopic particles allergens and volatile organic components (VOC's), and odorous gases.
Leitz TruSens Z-3000 Pet 3-in-1 Carbon Filter Leitz TruSens Z-3000 Pet 3-in-1 Carbon Filter
£40.99 exc vat | £49.19 inc vat | Stock : 10
Carbon filter is a replaceable element of the Pet HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, compatible with the Pet HEPA filter drum for all Leitz TruSens Z-13000 and Z-3500 air purifiers.
Leitz TruSens Z-3000 Pet 3-in-1 HEPA Filter Drum Leitz TruSens Z-3000 Pet 3-in-1 HEPA Filter Drum
£88.49 exc vat | £106.19 inc vat | Only 9 left
HEPA filter with washable pre-filter, efficiency level of 99.97% at 0.3 micron, 360 degree filtration, best for pet dander and odours, indicator light glows red on your air purifier when the filter needs to be replaced, Use with Z-3000 and Z-3500 Air Purifiers.
Leitz TruSens Z-3000 UV Bulb Leitz TruSens Z-3000 UV Bulb
£20.49 exc vat | £24.59 inc vat | Stock : 10
For use with the Leitz TruSens Z-3000 Air Purifier, UV reduces the growth of odour-causing microbes, indicator light on the air purifier glows red when it's time to replace the bulb. An important part of the air purification system, a UV bulb destroys germs and bacteria.
Leitz TruSens Z-3500 SMART Air Purifier with SensorPod Leitz TruSens Z-3500 SMART Air Purifier with SensorPod
£159.99 exc vat | £191.99 inc vat | Only 6 left
Simple Touch Controls, External wireless SensorPod, Automatically adjusts fan speed, 360-degree filtration, PureDirect airflow technology, Carbon / HEPA / UV filters types, timer option. Breathe cleaner air with a reimagined air purifier.
Leitz TruSens Z1000 HEPA Filter Drum Leitz TruSens Z1000 HEPA Filter Drum
£24.49 exc vat | £29.39 inc vat | Stock : 21
For use with the TruSens Z-1000 Air Purifier, 360 degree filtration, carbon prefilter captures odours and certain gases, HEPA Type filter removes pollutants as small as 0.3 microns, truSens combination filter has been engineered to collect microscopic particles allergens and volatile organic components (VOC's), and odorous gases.
Leitz TruSens Z1000 Odour and VOC 3-in-1 Carbon Filter Leitz TruSens Z1000 Odour and VOC 3-in-1 Carbon Filter
£27.99 exc vat | £33.59 inc vat | Stock : 41
Carbon filter is a replaceable element of the Odour and VOC HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, best for odours and VOCs, Compatible with the Z-1000 air purifiers.
Leitz TruSens Z1000 Odour and VOC 3-in-1 HEPA Filter Drum Leitz TruSens Z1000 Odour and VOC 3-in-1 HEPA Filter Drum
£43.49 exc vat | £52.19 inc vat | Only 6 left
3-layer carbon pellet filter surrounds the HEPA filter, Best for odours and VOCs, 360 degree filtration, for best results replace the Odour and VOC HEPA filter drum every 12 months (depending on usage), use with Z-1000 Air Purifier.
Leitz TruSens Z2000 Allergy and Flu Anti-Viral 3-in-1 HEPA Filter Drum Leitz TruSens Z2000 Allergy and Flu Anti-Viral 3-in-1 HEPA Filter Drum
£60.99 exc vat | £73.19 inc vat | Stock : 27
HEPA filter with anti-viral coating, 360 degree filtration, best for allergies and flu, efficiency level of 99.97% at 0.3 micron, captures airborne allergens and viruses including the H1N1 flu virus, for use with the Z-2000 and Z-2500 Air Purifiers.
Leitz TruSens Z2000 Odour and VOC 3-in-1 Carbon Filter Leitz TruSens Z2000 Odour and VOC 3-in-1 Carbon Filter
£39.79 exc vat | £47.75 inc vat | Stock : 10
Carbon filter is a replaceable element of the Odour and VOC HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, best for odours and VOCs, Compatible with the Z-2000 and Z-2500 air purifiers.
Leitz TruSens Z2000 Odour and VOC 3-in-1 HEPA Filter Drum Leitz TruSens Z2000 Odour and VOC 3-in-1 HEPA Filter Drum
£60.99 exc vat | £73.19 inc vat | Only 1 left
3-layer carbon pellet filter surrounds the HEPA filter, Best for odours and VOCs, 360 degree filtration, for best results replace the Odour and VOC HEPA filter drum every 12 months (depending on usage), use with Z-2000 and Z-2500 Air Purifiers.
Leitz TruSens Z2000 Particulate Air Filter [Pack of 3] Leitz TruSens Z2000 Particulate Air Filter [Pack of 3]
£13.79 exc vat | £16.55 inc vat | Only 2 left
For use with the TruSens Z-2000 Air Purifier, for best results replace carbon layer filter every 3 months, pack of 3 filters. For use with the TruSens Z-2000 Air Purifier. Filter replacement is essential for your air purifier to perform at its best.
Leitz TruSens Z3000 Allergy and Flu Anti-viral 3-in-1 HEPA Filter Drum Leitz TruSens Z3000 Allergy and Flu Anti-viral 3-in-1 HEPA Filter Drum
£75.49 exc vat | £90.59 inc vat | Only 1 left
HEPA filter with anti-viral coating, 360 degree filtration, best for allergies and flu, efficiency level of 99.97% at 0.3 micron, captures airborne allergens and viruses including the H1N1 flu virus, for use with the Z-3000 and Z-3500 Air Purifiers.
Leitz TruSens Z3000 HEPA Filter [Pack of 3] Leitz TruSens Z3000 HEPA Filter [Pack of 3]
£15.79 exc vat | £18.95 inc vat | Only 1 left
For use with the TruSens Z-3000 Air Purifier, for best results replace carbon layer filter every 3 months, pack of 3 filters. *** CLEARANCE ITEM - LIMITED STOCK AVAILABILITY AT THIS PRICE *** For use with the TruSens Z-3000 Air Purifier.
Leitz TruSens Z3000 Odour and VOC 3-in-1 Carbon Filter Leitz TruSens Z3000 Odour and VOC 3-in-1 Carbon Filter
£51.49 exc vat | £61.79 inc vat | Stock : 10
Carbon filter is a replaceable element of the Odour and VOC HEPA drum filter, indicator light glows red on your air purifier when the filter needs to be replaced, best for odours and VOCs, Compatible with the Z-3000 and Z-3500 air purifiers.
Leitz TruSens Z3000 Odour and VOC 3-in-1 HEPA Filter Drum Leitz TruSens Z3000 Odour and VOC 3-in-1 HEPA Filter Drum
£88.49 exc vat | £106.19 inc vat | Stock : 10
3-layer carbon pellet filter surrounds the HEPA filter, Best for odours and VOCs, 360 degree filtration, for best results replace the Odour and VOC HEPA filter drum every 12 months (depending on usage), use with Z-3000 and Z-3500 Air Purifiers.